A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Aquivalence revisited — New model formulation and application to assess environmental fate of ionic pharmaceuticals in Hamilton Harbour, Lake Ontario
Abstract A model formulation based on “aquivalence”, as defined in terms of activity is presented to estimate the multimedia fate of ionizing chemicals. The aquivalence approach is analogous to fugacity but aquivalence is applicable to neutral and ionizing compounds, and has been applied previously to speciating chemicals, notably metals. The new aquivalence-based mass-balance model treats ionizing organic compounds that exist as interconverting neutral and ionic species which are subject to fate processes at differing rates. The model is illustrated by application to four ionizing pharmaceuticals in Hamilton Harbour, Lake Ontario. At the system pH of 7.9–8.5, ibuprofen, gemfibrozil, and naproxen are expected to be almost entirely ionic and triclosan split between ionic and neutral forms. Measured seasonal surface water concentrations, which were 2–10 times lower in the late summer and fall than during spring, were used to solve for unknown values of chemical half-life in the water column due to degradation (photo- and bio-) of the ionizing and neutral forms and secondarily, ionic sorption coefficients of the ionizing forms. Model estimates of half-lives in the habour's water ranged from 11 to 77, 11 to 147 and 10 to 37 for ionic ibuprofen, gemfibrozil, and naproxen, respectively; and 4–22days and 2–9days for ionic and neutral triclosan, respectively, with the shortest half-lives in spring and the longest in summer.
Research highlights ► Fugacity-type models are widely used but are inappropriate for non-volatile compounds. ► “Aquivalence” is an alternative to fugacity for modeling non-volatile chemicals. ► An aquivalence model is presented to include differing fates of interconverting species. ► Model is applied to pharmaceuticals ibuprofen, gemfibrozil, naproxen, triclosan. ► The model estimated that half-lives in water ranged from 2–147 d for the compounds.
Aquivalence revisited — New model formulation and application to assess environmental fate of ionic pharmaceuticals in Hamilton Harbour, Lake Ontario
Abstract A model formulation based on “aquivalence”, as defined in terms of activity is presented to estimate the multimedia fate of ionizing chemicals. The aquivalence approach is analogous to fugacity but aquivalence is applicable to neutral and ionizing compounds, and has been applied previously to speciating chemicals, notably metals. The new aquivalence-based mass-balance model treats ionizing organic compounds that exist as interconverting neutral and ionic species which are subject to fate processes at differing rates. The model is illustrated by application to four ionizing pharmaceuticals in Hamilton Harbour, Lake Ontario. At the system pH of 7.9–8.5, ibuprofen, gemfibrozil, and naproxen are expected to be almost entirely ionic and triclosan split between ionic and neutral forms. Measured seasonal surface water concentrations, which were 2–10 times lower in the late summer and fall than during spring, were used to solve for unknown values of chemical half-life in the water column due to degradation (photo- and bio-) of the ionizing and neutral forms and secondarily, ionic sorption coefficients of the ionizing forms. Model estimates of half-lives in the habour's water ranged from 11 to 77, 11 to 147 and 10 to 37 for ionic ibuprofen, gemfibrozil, and naproxen, respectively; and 4–22days and 2–9days for ionic and neutral triclosan, respectively, with the shortest half-lives in spring and the longest in summer.
Research highlights ► Fugacity-type models are widely used but are inappropriate for non-volatile compounds. ► “Aquivalence” is an alternative to fugacity for modeling non-volatile chemicals. ► An aquivalence model is presented to include differing fates of interconverting species. ► Model is applied to pharmaceuticals ibuprofen, gemfibrozil, naproxen, triclosan. ► The model estimated that half-lives in water ranged from 2–147 d for the compounds.
Aquivalence revisited — New model formulation and application to assess environmental fate of ionic pharmaceuticals in Hamilton Harbour, Lake Ontario
Csiszar, Susan A. (author) / Gandhi, Nilima (author) / Alexy, Radka (author) / Benny, Donald T. (author) / Struger, John (author) / Marvin, Chris (author) / Diamond, Miriam L. (author)
Environmental International ; 37 ; 821-828
2011-02-01
8 pages
Article (Journal)
Electronic Resource
English
Numerical models of the exchange flows between Hamilton Harbour and Lake Ontario
| Online Contents | 2003
Results of in-situ capping demonstration project in Hamilton Harbour, Lake Ontario, Canada
| British Library Conference Proceedings | 1997